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Continuing Education Activity

Imatinib is a 2-phenylamino-pyrimidine derivative protein that is a medication used to manage and treat chronic myelogenous leukemia, gastrointestinal stromal tumors, and other malignancies. It is in the tyrosine-kinase inhibitors class of drugs. This activity reviews the indications, action, and contraindications for imatinib as a valuable agent in the treatment of several oncologic indications. In addition, this activity will highlight the mechanism of action, adverse event profile, and other key factors (e.g., dosing, administration, monitoring, relevant interactions, and toxicity) pertinent for members of the healthcare team for treating patients with chronic myelogenous leukemia, gastrointestinal stromal tumors, and other related conditions.


  • Identify the mechanism of action of imatinib.
  • Describe the potential adverse effects of imatinib.
  • Review the appropriate monitoring/toxicity of imatinib, including significant drug interactions.
  • Explain interprofessional team strategies for improving care coordination and communication to improve outcomes for patients receiving imatinib.


Imatinib mesylate (Imatinib) is an oral tyrosine kinase inhibitor that initially received FDA approval for chronic myelogenous leukemia in 2001. Subsequently, it has received approval to treat several other oncologic conditions. Currently, FDA-approved indications include:

  • First-line adult and pediatric Philadelphia chromosome-positive chronic myelogenous leukemia in chronic phase (Ph+ CML CP)
    • IRIS Trial: treatment with imatinib in adults with newly diagnosed CML resulted in a 10-year overall survival rate of 83.3%.[1]    
  • Philadelphia chromosome-positive chronic myelogenous leukemia in blast crisis (Ph+ CML BC)
    • In a single-arm phase 2 study of Ph+ CML BC patients, imatinib induced a major cytogenetic response in 16% of patients and a complete hematologic response in 52% of patients.[2]
  • Philadelphia chromosome-positive chronic myelogenous leukemia in accelerated phase (Ph+ CML AP):
    • In a single-arm phase 2 study of Ph+ CML AP patients, imatinib induced a significant cytogenetic response in 24% of patients and a complete hematologic response in 82% of patients.[3]
  • Philadelphia chromosome-positive chronic myelogenous leukemia in chronic phase after failure of interferon-alpha therapy
    • In a single-arm phase 2 study of Ph+ CML CP treatment failures with interferon-alpha, imatinib induced a significant cytogenetic response in 60% of patients and a complete hematologic response in 95% of patients.[4]
  • Adult relapsed/refractory Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL)
    • In a single-arm phase 2 study of relapsed/refractory Ph+ ALL patients, imatinib induced a complete cytogenetic response in 17% of patients and a complete hematologic response in 19% of patients.[5]
  • First-line pediatric Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) in combination with chemotherapy
    • AALL0031 Trial: treatment with imatinib plus chemotherapy resulted in 5-year disease-free survival of 70% compared to a 65% rate in the sibling donor bone-marrow transplant cohort.[6]
  • Adult myelodysplastic (MDS)/myeloproliferative (MPD) diseases associated with platelet-derived growth factor receptor gene re-arrangements
    • In an open-label phase 2 study, an additional study, and 12 published case report in adult myelodysplastic(MDS)/myeloproliferative(MPD) disease associated with platelet-derived growth factor receptor gene re-arrangements, imatinib induced a major cytogenetic response in 39% of patients and a complete hematologic response in 45% of patients.
  • Adult aggressive systemic mastocytosis (ASM) without D816V c-Kit mutations (or unknown c-Kit mutational status)
    • In a phase 2 study and ten published case reports, imatinib induced a complete hematologic response in 29% of patients.
  • Adult hypereosinophilic syndrome (HES) or chronic eosinophilic leukemia (CEL) with FIP1L1-PDGFR-alpha fusion kinase and for patients with hypereosinophilic syndrome and/or chronic eosinophilic leukemia who are FIP1L1-PDGFR-alpha fusion kinase negative or unknown
    • In a phase 2 study and 35 published case reports, treatment with imatinib induced a complete hematologic response in 61% of patients.
  • Adult unresectable, recurrent, and/or metastatic dermatofibrosarcoma protuberans (DFSP)
    • In a phase 2 study and five published case reports, treatment with imatinib induced an 83% response rate, including a 39% complete response rate. 
  • Kit positive unresectable and/or metastatic malignant gastrointestinal stromal tumors (GIST)
    • In two large randomized phase 3 clinical trials of patients with Kit positive unresectable and/or metastatic malignant GIST, treatment with imatinib 400mg/day resulted in a 1.58 year(18.9 months) progression-free survival and a 4.08 year(49.0 months) overall survival.[7]
  • Adult adjuvant treatment following resection of Kit positive GIST
    • In a randomized, double-blind, placebo-controlled phase 3 trial of adult adjuvant treatment following the resection of Kit positive GIST, imatinib therapy resulted in a recurrence-free survival of 98% at one year compared to placebo at 83%, p<0.0001, hazard ratio = 0.35.[8]

Mechanism of Action

Imatinib mesylate is a 2-phenylamino-pyrimidine derivative protein and tyrosine kinase inhibitor initially targeted to the platelet-derived growth factor receptor.[9] Subsequently, it has also been found to inhibit other protein tyrosine kinases such as c-kit (gastrointestinal stromal tumors) and BCR-ABL fusion protein (Philadelphia chromosome chronic myelogenous leukemia). These protein tyrosine kinases as a whole phosphorylate specific amino acids on substrate proteins, which induce signal transduction resulting in changes to cell biology, including cell growth, differentiation, and death, constitutive activation of which, through mutation or other means, can lead to malignancy.[10]

Blocking this constitutive action has been shown to induce downstream apoptosis without further differentiation.[11] Imatinib, as a therapeutic, blocks the constitutive action of protein tyrosine kinase by working as a competitive inhibitor of the ATP binding cleft of ABL, inducing apoptosis of leukemic cells.[12]


Imatinib is FDA-approved to be administered orally and is typically supplied in 100 mg and 400 mg tablet formulations. Imatinib was initially available under a branded name; however, after the expiration of several patents, generic versions are available. The recommended dosing for imatinib varies by indication:

  • Adult Ph+ CML CP 400 mg/day
  • Adult Ph+ CML AP 600 mg/day
  • Adult Ph+ CML BC 600 mg/day
  • Pediatric Ph+ CML 340 mg/m2/day
  • Adult Ph+ ALL 600 mg/day
  • Adult MDS 400 mg/day
  • Adult MPD 400 mg/day
  • Adult ASM 100 mg/day or 400mg/day
  • Adult HES 100 mg/day or 400mg/day
  • Adult CEL 100 mg/day or 400mg/day
  • Adult DFSP 800 mg/day
  • Adult metastatic/unresectable GIST 400 mg/day
  • Adult adjuvant GIST 400 mg/day
  • Mild to moderate hepatic impairment 400 mg/day
  • Severe hepatic impairment 300 mg/day

800 mg doses should be administered as a 400 mg dose twice daily; all other doses should be given once daily. Patients should take imatinib with meals and a large glass of water to minimize gastrointestinal upset, and food does not impact bioavailability.[13]

Adults of Reproductive Potential

Human post-marketing surveillance and animal studies have shown imatinib to harm the developing fetus. Therefore, clinicians should test pregnancy status in females with reproductive potential before the initiation of treatment.


Advise females of reproductive potential to administer effective contraception (methods resulting in less than 1% pregnancy rates) while using imatinib during treatment and for two weeks days after stopping treatment with imatinib.

Pregnancy Considerations

Based on human and animal data, imatinib can cause fetal harm when administered to a pregnant woman. There are no clinical studies on the use of imatinib in pregnant women. However, there have been postmarket reports of spontaneous abortions and congenital anomalies from women who have been exposed to imatinib during pregnancy. Therefore, advise females to avoid pregnancy when taking imatinib. If imatinib is administered during pregnancy, or if the female gets pregnant while taking it, counsel the patient about the potential hazard for the fetus.[14][15]

Breastfeeding Considerations

Imatinib and its metabolite are excreted into breast milk. Since there is potential for serious adverse reactions in breastfed infants from imatinib, advise a lactating woman not to breastfeed during treatment and for one month after the last dose.[16][17]

Hepatic Impairment

Mild and moderate hepatic impairment do not affect exposure to imatinib and metabolite CGP74588. However, in patients with severe hepatic impairment, the imatinib AUC increased by 45%, and the CGP74588 AUC increased by 55%, compared to patients with normal hepatic function. Therefore, reduce the dose of imatinib by 25% for patients with severe hepatic impairment.

Renal Impairment

There is insufficient data on patients with severe renal impairment, and as per the manufacturer’s labeling, dose reductions are required for patients with moderate and/or severe renal impairment.

Adverse Effects

Clinically Significant Warnings and Precautions

There are several clinically relevant precautions with imatinib use.[18] These include:

  • Dermatologic: including cases of Stevens-Johnson syndrome (SJS) and erythema multiforme (although the etiology of imatinib causing SJS is unclear)
  • Embryo-fetal toxicity
  • Fluid retention and edema
  • Gastrointestinal disorders and perforations
  • Growth retardation in children
  • Hematologic toxicity (anemia, neutropenia, thrombocytopenia)
  • Hemorrhage (gastrointestinal and intra-tumoral grade 3/4 hemorrhages)
  • Hepatotoxicity
  • Hypereosinophilic cardiac toxicity (cardiogenic shock and left ventricular dysfunction have been reported in HES patients initiating imatinib therapy)
  • Hypothyroidism
  • Long-term use toxicity (cardiac, kidney, and liver toxicities suggested by animal studies)
  • Pregnancy (category D – avoid pregnancy while taking imatinib)
  • Renal toxicity
  • Severe congestive heart failure with left ventricular dysfunction
  • Tumor lysis syndrome

Common Side Effects That Occurred in Over 10% of Clinical Trial Participants

Imatinib has a long list of potential adverse events.[8][5] The following list many of the most relevant examples: 

  • Abdominal pain/distention
  • Alanine aminotransferase increase
  • Alopecia
  • Anemia
  • Anorexia
  • Arthralgia
  • Aspartate aminotransferase increase
  • Asthenia
  • Blood creatine increase
  • Blood lactate dehydrogenase increase
  • Bone pain
  • Constipation
  • Cough
  • Depression
  • Diarrhea
  • Dizziness
  • Dyspepsia
  • Dyspnea
  • Fatigue
  • Flatulence
  • Fluid retention
  • Headache
  • Hemoglobin decrease
  • Hemorrhage (non-GI/CNS)
  • Hypoalbuminemia
  • Hypokalemia
  • Hypoproteinemia
  • Infection
  • Influenza
  • Insomnia
  • Joint pain
  • Muscle cramps/spasms
  • Musculoskeletal pain
  • Myalgia
  • Nasopharyngitis
  • Nausea
  • Neutropenia
  • Night sweats
  • Pain
  • Peripheral edema
  • Periorbital edema
  • Pharyngolaryngeal pain
  • Pneumonia
  • Pruritis
  • Pyrexia
  • Rhinitis
  • Rigors
  • Skin rash
  • Sinusitis
  • Thrombocytopenia
  • Upper respiratory tract Infection
  • Vision, blurred
  • Vomiting
  • Weight increase
  • White blood cell decrease


There are no contraindications for imatinib.

Imatinib gets metabolized through the enzyme cytochrome p450 3A4 (CYP3A4).[19] 

  • Administration of imatinib with CYP3A4 inducers may reduce total imatinib exposure.
  • Administration of imatinib with CYP3A4 inhibitors may increase total imatinib exposure.
  • Avoid grapefruit juice as it can potentially increase the plasma concentration of imatinib.
  • Imatinib will increase plasma concentrations of other CYP3A4 metabolized drugs.


  • Monitor patients regularly for the signs and symptoms of fluid retention.
  • Monitor patients for signs and symptoms of cardiac or renal failure, especially in those with a history of cardiac disease or renal failure
  • Monitor liver function (alkaline phosphatase, bilirubin, and transaminases) before starting treatment and then monthly afterward or as indicated going forward
  • Monitor hepatic function
  • Monitor TSH levels in patients after thyroidectomy[20]
  • Monitor growth in children
  • Monitor patients with a high proliferative rate or high tumor burden for tumor lysis syndrome
  • Monitor renal function before starting therapy and on an ongoing basis, especially in those with congestive heart failure, diabetes mellitus, or pre-existing renal impairment
  • Monitor complete blood counts for evidence of hematologic toxicity (anemia, neutropenia, and thrombocytopenia)


  • Treatment with imatinib is associated with hematologic toxicity (anemia, neutropenia, and thrombocytopenia)
  • Treatment with imatinib is associated with hepatotoxicity.
  • Treatment with imatinib is associated with hypereosinophilic cardiac toxicity in patients with hypereosinophilic syndrome.
  • Treatment with imatinib can cause fetal harm to a pregnant woman (Imatinib has demonstrated teratogenicity in rats at the 800 mg/day equivalent human maximum dose)[14]
  • Treatment with imatinib is associated with renal toxicity.
  • Treatment with imatinib is associated with dermatologic toxicities, including erythema multiforme and Stevens-Johnson syndrome.[18]

Enhancing Healthcare Team Outcomes

Imatinib is a powerful targeted therapeutic drug for several types of cancer. Despite showing a favorable risk/benefit tradeoff in several clinical trials and being FDA-approved for nearly two decades, it does require close monitoring for safety. In addition to the prescribing physician, pharmacists and nurses are responsible for educating the patient on the potential side effects of the drug. While most side effects occur in the first two years of use, many patients will be on chronic therapy for many years, so it is essential to stay vigilant in monitoring for side effects.[20] 

Particularly severe side effects that require careful monitoring include Stevens-Johnson syndrome, gastrointestinal perforations/hemorrhage, fluid retention, organ (cardiac, renal, and liver) failure, and hematologic toxicities. Additionally, imatinib does have several interactions with other medications that are also metabolized by CYP3A4. The pharmacist needs to monitor all medications the patient takes to ensure no interactions. This requires proper dose adjustments due to potential drug-drug interactions if concurrent medications are necessary. The clinicians, nurses, and pharmacists should regularly check liver function, renal function, and complete blood counts to monitor for organ damage or immunosuppression and adjust imatinib dosing as necessary while continually informing the ordering clinician.

Nursing will notably have the optimal chance to see any issues that arise since they will have the first contact with the patient, so they must be familiar with the adverse event and interaction profile. This is where an oncology specialty nurse is invaluable. All interprofessional team members are responsible for monitoring the patient's progress and reporting any status changes to the rest of the team so corrective measures can be taken if necessary. This also includes meticulous documentation so that everyone on the healthcare team has the same patient data set from which to work. This collaborative paradigm exemplifies the type of interprofessional teamwork the healthcare team requires to administer imatinib effectively to achieve optimal patient outcomes while minimizing patient risks. [Level 5]

It was one of the first targeted therapeutics to reach the market and also now is generic. Imatinib presents interesting time-series data on the costs of precision medications. At approval in 2001, a one-month supply of the 400mg daily dose cost $2200 in the US.[21] In 2010, this cost had ballooned to $5143 per month, and by 2018 it was $10620 per month.[22] A generic form of imatinib was launched in the US in 2015 at a 30% discount on the branded price (which was substantially higher than the 82% discount at which the Canadian generic was launched).[23]

Because of dysfunctional market maximizing forces, ironically, the price of imatinib generics was higher than the original branded version, and pricing relief remained elusive for years. However, during 2018, generic imatinib pricing finally dropped below its original launch price, yet it still cost several thousand dollars per annum despite being generic. With expensive therapies such as imatinib, the interprofessional healthcare team, including clinicians, nurses, pharmacists, and other healthcare professionals (such as social workers or charity assistance programs), must coordinate care and advocate for coverage to maximize access to life-saving medications.

Article Details

Article Author

James P. Flynn

Article Editor:

Valerie Gerriets


7/2/2022 1:59:51 PM



Hochhaus A,Larson RA,Guilhot F,Radich JP,Branford S,Hughes TP,Baccarani M,Deininger MW,Cervantes F,Fujihara S,Ortmann CE,Menssen HD,Kantarjian H,O'Brien SG,Druker BJ, Long-Term Outcomes of Imatinib Treatment for Chronic Myeloid Leukemia. The New England journal of medicine. 2017 Mar 9;     [PubMed PMID: 28273028]


Sawyers CL,Hochhaus A,Feldman E,Goldman JM,Miller CB,Ottmann OG,Schiffer CA,Talpaz M,Guilhot F,Deininger MW,Fischer T,O'Brien SG,Stone RM,Gambacorti-Passerini CB,Russell NH,Reiffers JJ,Shea TC,Chapuis B,Coutre S,Tura S,Morra E,Larson RA,Saven A,Peschel C,Gratwohl A,Mandelli F,Ben-Am M,Gathmann I,Capdeville R,Paquette RL,Druker BJ, Imatinib induces hematologic and cytogenetic responses in patients with chronic myelogenous leukemia in myeloid blast crisis: results of a phase II study. Blood. 2002 May 15;     [PubMed PMID: 11986204]


Talpaz M,Silver RT,Druker BJ,Goldman JM,Gambacorti-Passerini C,Guilhot F,Schiffer CA,Fischer T,Deininger MW,Lennard AL,Hochhaus A,Ottmann OG,Gratwohl A,Baccarani M,Stone R,Tura S,Mahon FX,Fernandes-Reese S,Gathmann I,Capdeville R,Kantarjian HM,Sawyers CL, Imatinib induces durable hematologic and cytogenetic responses in patients with accelerated phase chronic myeloid leukemia: results of a phase 2 study. Blood. 2002 Mar 15;     [PubMed PMID: 11877262]


Kantarjian H,Sawyers C,Hochhaus A,Guilhot F,Schiffer C,Gambacorti-Passerini C,Niederwieser D,Resta D,Capdeville R,Zoellner U,Talpaz M,Druker B,Goldman J,O'Brien SG,Russell N,Fischer T,Ottmann O,Cony-Makhoul P,Facon T,Stone R,Miller C,Tallman M,Brown R,Schuster M,Loughran T,Gratwohl A,Mandelli F,Saglio G,Lazzarino M,Russo D,Baccarani M,Morra E, Hematologic and cytogenetic responses to imatinib mesylate in chronic myelogenous leukemia. The New England journal of medicine. 2002 Feb 28;     [PubMed PMID: 11870241]


Ottmann OG,Druker BJ,Sawyers CL,Goldman JM,Reiffers J,Silver RT,Tura S,Fischer T,Deininger MW,Schiffer CA,Baccarani M,Gratwohl A,Hochhaus A,Hoelzer D,Fernandes-Reese S,Gathmann I,Capdeville R,O'Brien SG, A phase 2 study of imatinib in patients with relapsed or refractory Philadelphia chromosome-positive acute lymphoid leukemias. Blood. 2002 Sep 15;     [PubMed PMID: 12200353]


Schultz KR,Carroll A,Heerema NA,Bowman WP,Aledo A,Slayton WB,Sather H,Devidas M,Zheng HW,Davies SM,Gaynon PS,Trigg M,Rutledge R,Jorstad D,Winick N,Borowitz MJ,Hunger SP,Carroll WL,Camitta B, Long-term follow-up of imatinib in pediatric Philadelphia chromosome-positive acute lymphoblastic leukemia: Children's Oncology Group study AALL0031. Leukemia. 2014 Jul;     [PubMed PMID: 24441288]


Comparison of two doses of imatinib for the treatment of unresectable or metastatic gastrointestinal stromal tumors: a meta-analysis of 1,640 patients. Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2010 Mar 1;     [PubMed PMID: 20124181]


Dematteo RP,Ballman KV,Antonescu CR,Maki RG,Pisters PW,Demetri GD,Blackstein ME,Blanke CD,von Mehren M,Brennan MF,Patel S,McCarter MD,Polikoff JA,Tan BR,Owzar K, Adjuvant imatinib mesylate after resection of localised, primary gastrointestinal stromal tumour: a randomised, double-blind, placebo-controlled trial. Lancet (London, England). 2009 Mar 28;     [PubMed PMID: 19303137]


Savage DG,Antman KH, Imatinib mesylate--a new oral targeted therapy. The New England journal of medicine. 2002 Feb 28;     [PubMed PMID: 11870247]


Kolibaba KS,Druker BJ, Protein tyrosine kinases and cancer. Biochimica et biophysica acta. 1997 Dec 9;     [PubMed PMID: 9426205]


Gambacorti-Passerini C,le Coutre P,Mologni L,Fanelli M,Bertazzoli C,Marchesi E,Di Nicola M,Biondi A,Corneo GM,Belotti D,Pogliani E,Lydon NB, Inhibition of the ABL kinase activity blocks the proliferation of BCR/ABL leukemic cells and induces apoptosis. Blood cells, molecules     [PubMed PMID: 9446752]


le Coutre P,Mologni L,Cleris L,Marchesi E,Buchdunger E,Giardini R,Formelli F,Gambacorti-Passerini C, In vivo eradication of human BCR/ABL-positive leukemia cells with an ABL kinase inhibitor. Journal of the National Cancer Institute. 1999 Jan 20;     [PubMed PMID: 9923858]


Peng B,Lloyd P,Schran H, Clinical pharmacokinetics of imatinib. Clinical pharmacokinetics. 2005;     [PubMed PMID: 16122278]


El Gendy MM,Kandil AM,Helal MA,Zahou FM, The teratogenic effects of imatinib mesylate on rat fetuses. Toxicology reports. 2015;     [PubMed PMID: 28962401]


Alizadeh H,Jaafar H,Kajtár B, Outcome of 3 pregnancies in a patient with chronic myeloid leukemia who received 3 types of tyrosine kinase inhibitors each in different pregnancy: follow-up of the case with a review of published reports. Annals of Saudi medicine. 2015 Nov-Dec     [PubMed PMID: 26657232]


Pistilli B,Bellettini G,Giovannetti E,Codacci-Pisanelli G,Azim HA Jr,Benedetti G,Sarno MA,Peccatori FA, Chemotherapy, targeted agents, antiemetics and growth-factors in human milk: how should we counsel cancer patients about breastfeeding? Cancer treatment reviews. 2013 May     [PubMed PMID: 23199900]


Deininger MW,Shah NP,Altman JK,Berman E,Bhatia R,Bhatnagar B,DeAngelo DJ,Gotlib J,Hobbs G,Maness L,Mead M,Metheny L,Mohan S,Moore JO,Naqvi K,Oehler V,Pallera AM,Patnaik M,Pratz K,Pusic I,Rose MG,Smith BD,Snyder DS,Sweet KL,Talpaz M,Thompson J,Yang DT,Gregory KM,Sundar H, Chronic Myeloid Leukemia, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology. Journal of the National Comprehensive Cancer Network : JNCCN. 2020 Oct 1     [PubMed PMID: 33022644]


Jha P,Himanshu D,Jain N,Singh AK, Imatinib-induced Stevens-Johnsons syndrome. BMJ case reports. 2013 Jan 23;     [PubMed PMID: 23349042]


Cohen MH,Williams G,Johnson JR,Duan J,Gobburu J,Rahman A,Benson K,Leighton J,Kim SK,Wood R,Rothmann M,Chen G,U KM,Staten AM,Pazdur R, Approval summary for imatinib mesylate capsules in the treatment of chronic myelogenous leukemia. Clinical cancer research : an official journal of the American Association for Cancer Research. 2002 May;     [PubMed PMID: 12006504]


Mughal TI,Schrieber A, Principal long-term adverse effects of imatinib in patients with chronic myeloid leukemia in chronic phase. Biologics : targets     [PubMed PMID: 21209726]


The price of drugs for chronic myeloid leukemia (CML) is a reflection of the unsustainable prices of cancer drugs: from the perspective of a large group of CML experts. Blood. 2013 May 30;     [PubMed PMID: 23620577]


Dusetzina SB,Huskamp HA,Keating NL, Specialty Drug Pricing and Out-of-Pocket Spending on Orally Administered Anticancer Drugs in Medicare Part D, 2010 to 2019. JAMA. 2019 May 28;     [PubMed PMID: 31135837]


Chen CT,Kesselheim AS, Journey of Generic Imatinib: A Case Study in Oncology Drug Pricing. Journal of oncology practice. 2017 Jun;     [PubMed PMID: 28445102]